12 



19. Involucre burr-like 61— Cenchrus. 



20. Paleae with awns one to three times their length, 3 — Alopecurus. 



20. Paleae with awns five times their length 44 — Hordeum. 



21. Both glumes and paleae awned 10— Muhlenbergia. 



21. Glumes awnless, single paleae awned, 54— Anthoxanthura. 



21. Paleae two. lateral flowers staminate 53— Hierochloa. 



22. Flowers perfect or pnlygotaus, 23 



22. Spikes monoecious 25 



23. Spikes one-sided, 24 



2D. Spikes cylindrical, solitary terminal, 4 — Phleum. 



21. Spikes two or more. spikelets suborbicular, 58 Paspalum 



24, ,. digitate or verticillatc. linear * aspalum 



24, " pedunculate, in a two-sided panicl Spartina. 



24. ., sessile, in a one-sided panicle Lepturus* 



25, '• all terminal, sterile above, fertile at the base Tripsacum. 



25. Fertile spikes lateral, sterile ones terminal panicled Zea. 



26. Inflorescence in panicles 27, 



26. Inflorescense in spikes 39. 



27. Flowers awned 28. 



27 Flowers without awns 33. 



28. Lower palea awned on the back .... 29. 



28, " " awned on apex 32. 



29. Awn near the base of the palea „.30. 



29. Awn near the apex of the palea 31. 



30, Apex bifid, awn bent Avena. 



30, " " " " lower flower sterile Arrhenatherum. 



30. " multifid Air a. 



31. Palea with two bristly teeth Trisetum . 



31. Palea bifid Bromus. 



22. Lower palea rounded, obtuse Briza. 



32. " " entire, pointed, fruit coated Festuca. 



32. Awn between two teeth, twisted Danthonia. 



38. Terminal flower perfect 34. 



33. " " abortive, or a mere pedicel 36 



34. Palea entire, outer one mucronate 35. 



34. Glumes unequal, like the lower abortive pale Panicum. 



34. " equal, longer than the palea , Phalaris. 



34. Lower palea truncate-mucrouate. inner bifid ..Uuiola. 



34. Flowers silky-bearded on the rachis Phragmites. 



34. Spikelets terete, palea 7-nerved Glyceria. 



34, " two to six, five-nerved , Poa. 



34. " " twenty, three-nerved Eragrostis 



34. " flat, lower pale laterally compressed Distichlis or Brizoyyrum. 



35. Scales two styles two Festuca. 



36. ,' one " three Arundinaria. 



36. Panicle contracted 37. 



85. " large diffuse Melica. 



37. Lower palea 1-pointed, or mucronate 38 . 



37. " " pointless Eatonia. 



37. " " three cleft Triodia or Tricuspis. 



37. " ,' awnless Dupontia. 



3«. Stamens three Koeleria. 



38. ,' two Diarrhena. 



89 spikelets two-ranked " 37. 



:;9. " unilateral... 43- 



40. Glumes broad ..41. 



40. " subiculate 42. 



40. " none Asprella or Gymnostichum 



41. " two, in the upper spikelet only Lolium. 



41. " " in each spikelet Agropyrum or Triticum 



